This issue has been moved from a ticket on Developer Community.

[severity:It bothers me. A fix would be nice] [regression] [worked-in:16.4]
It should be with a red wavy underline, but nothing there.

Original Comments

(private comment, text removed)

Wenwen Fan [MSFT] on 28/04/2022, 04:18 PM:

Thank you for taking the time to log this issue!
Do you still reproduce this issue now? I can’t reproduce this problem in VS2022 Community (17.1.5) with below steps:
1.Click View> Other Windows > C# Interactive.
2.Enter int a="";under C# Interactive.
Result: It is underlined with a red wavy.
Did I miss some steps? If so, can you provide the detailed repro steps and a demo project that can be reproduced? Can you try updating to the latest VS?
We look forward to hearing from you!

flithor on 28/04/2022, 07:47 PM:

It looks like the feature “Enable pull diagnostics” of the advanced setting of c# text editor caused this issue.
Disable it:

Enable it: